This invention relates to the generation of hydrogen and oxygen from water using solar energy. According to the present invention, solar energy is converted into potential energy in the form of hydrogen and oxygen which may be in liquid or gaseous state, or as solid compound such as a metallic hydride. The uses of liquid oxygen are well known. Since demands on conventional non-replaceable fossil fuels have increased drastically over the recent decade, threatening the world supply of these natural resources and the cost of generation of electric and nuclear power have both increased drastically, it has become clear that a new fuel is needed. Hydrogen is readily available in water and fills this need. There are presently available engines and heating and power plants which can run on hydrogen.
In prior art devices such as that taught in U.S. Pat. No. 4,030,890, solar energy (sunlight) is converted into thermal energy (heat) through mechanical means and with attendant energy losses. This thermal energy is then transferred, with additional energy losses, through metallic interfaces to the reactant (water) until sufficient thermal energy has been transferred to the water to bring about its thermal decomposition. Such devices have several major disadvantages. They rely solely on thermal energy to promote dissociation. Thus, they do not take advantage of the ability of certain frequencies of the light spectrum, primarily the near ultraviolet wave ranges to fracture the molecular bonds in the molecules of water vapor, causing direct dissociation through the medium of wave form irradiation. This phenomenon is known as photolysis, or the photolytic effect of the ultraviolet radiation in sunlight upon the molecular bonds in water vapor molecules. When combined with the known effects of high thermal energy levels upon water vapor molecules to cause direct thermal decomposition of the water into elemental and molecular hydrogen and oxygen, the photolytic effect permits a given rate of decomposition to take place at lower temperatures, and with greater efficiency of energy utilization than if thermal energy alone is employed. The combined effects of high thermal energy and photolytic effect of ultraviolet radiation allow dissociation of water vapor to take place at a greater rate than if thermal energy alone is employed.
The mechanism through which this combined reaction takes place is believed to be as follows:
First, a portion of the concentrated incoming radiant energy (sunlight) primarily the infra-red frequencies (wave-lengths of approximately 10.sup.4 to 10.sup.6 angstroms) is converted to thermal energy (heat) upon contact with water vapor. This thermal energy is then absorbed by the molecules of the water vapor, agitating (heating) the water molecules and gradually increasing the frequency level of molecular vibrations to the level required for rupture of the molecular bonds and dissociation of the water molecules into their components. It is known that the level of thermal energy required for this molecular dissociation is extremely high, in excess of 3000.degree. K. at standard pressure.
Second, radiant wave form energy in the form of concentrated sunlight directly bombards the agitated molecular bonds of the water vapor molecules and the near ultra-violet wave lengths (approximately 10.sup.2 to 10.sup.3 angstroms) of the light spectrum directly excite the vibrational level of the molecular bonds beyond the level required for fracturing of the molecular bonds resulting in the dissociation of the water molecules into atoms, molecules and ions of hydrogen (H+,H.sub.2) and oxygen (O,O.sub.2), and hydroxyl radicals (OH). Thus, the near ultra-violet wave frequencies of the natural light spectrum can supply additional energy for breaking the molecular bonds in water vapor. Therefore, concentrated ultra violet energy in combination with high levels of thermal energy can allow a given rate of direct dissociation of the molecules of water vapor to take place at lower thermal energy levels and with greater energy utilization efficiencies than if thermal energy alone is employed. Conversely, at a given level of thermal energy, dissociation of water vapor molecules will proceed at a greater rate.
The present invention takes full advantage of both the thermal and photolytic properties of solar energy (sunlight).
Thus, this invention has significant advantages over other solar energy devices.
Direct dissociation of water molecules in my invention can take place at lower thermal energy levels and with greater energy utilization, thus smaller scale collection apparatus can be employed with equivalent results, with an attendant lower capital investment.
Since prior art devices transmit thermal energy to the water indirectly through the wall of a metallic container, there are substantial energy losses due to the conduction transfer through the container.
The concentrated solar energy initially impacts the container wall of previously known devices directly at the extremely high temperature levels required to (a) overcome energy transfer losses and (b) sustain the extremely high internal temperatures required for direct thermal dissociation. This requires that the container be constructed of materials capable of withstanding these extremely high temperature concentrations and the rapid upward and downward temperature excursions caused by abrupt fluctuations in the level of available sunlight over extended periods without undergoing catastrophic failure e.g. by fusion, thermal shock, fracture, corrosion, embrittlement, etc. Suitable materials such as tungsten not only are very expensive, but also are very difficult to machine and manufacture.
The method of the present invention causes the concentrated solar energy to interact directly with the water vapor in the reaction chamber, avoiding direct contact of the concentrated light beam with any portion of the reaction chamber structure. Therefore, less expensive materials can be used to contain the reaction.